JUBA - International pressure bore down Saturday on the two sides in South Sudan's bloody violence to open peace talks to keep the young nation from sliding into civil war.
East African and Horn of Africa peace brokers gave until December 31 for President Salva Kiir and de facto rebel leader Riek Machar, whom Kiir sacked as vice president in July, to start face-to-face talks and stop two weeks of fighting that is thought to have left thousands dead.
"We, government, are ready to meet even before that," South Sudan's Vice President James Wani Igga told reporters. "It's now up to Machar to accept the ceasefire."
The government on Saturday reiterated accusations that Machar was mobilising thousands of youths to attack its interests.
"Dr Riek mobilises his... youths, up to 25,000... and wants to use them to attack the government" in the eastern state of Jonglei, where rebels said to support Machar briefly captured the regional capital, Bor, earlier this month, government spokesman Michael Makuei told AFP.
"They are able to attack any time," he added. "We are in a state of alert to protect the civilian populations."
But Moses Ruai Lat, spokesman for the rebels, rejected this, saying the former vice-president was "not mobilising his tribe," the Nuer, South Sudan's second biggest ethnic group.
Those young people were regular soldiers turning their back on the government and had not been drafted by Machar, he added.
The regional grouping the Inter-Governmental Authority on Development is spearheading efforts to end the fierce battles for control over several strategic oil-producing areas notably in the north of South Sudan.
The United Nations, Washington and Beijing are also pressing for talks.
"IGAD has already come out with the condition that the contending parties should negotiate within four days beginning from Friday," Ethiopian foreign ministry spokesman Dina Mufti said Saturday.
"So we are awaiting results."
Spokesmen for IGAD said President Kiir had on Friday expressed willingness for an "immediate" ceasefire though Machar would not immediately commit to a truce.
The rebel leader said he first wanted a mechanism to monitor any ceasefire as well as the release of all his political allies arrested when trouble first broke out.
The conflict, fuelled by an old rivalry between Kiir and Machar, has fanned ethnic differences between Kiir's Dinka group and Machar's Nuer clan in the country, which won independence from Sudan in 2011.
Reports of massacres, rapes and murders have emerged in recent days. The United Nations -- whose hard-pressed peacekeepers are to be doubled to more than 12,000 -- said one mass grave had been discovered and large numbers of uncollected bodies were seen outside at least one UN base.
The fighting erupted December 15 after Kiir accused his former vice president of trying to mount a coup. Machar has denied the allegation and retorted that Kiir was trying to eliminate his rivals.
Rebels quickly took control of a few key regional cities including Bentiu, in the northern oil-producing state of Unity, as well as Bor which was recaptured by the army on Tuesday.
On Saturday, South Sudan army spokesman Philip Aguer told AFP that all was calm in the main flashpoint areas of recent days, including Malakal, capital of the oil-rich northeastern Upper Nile state, in Bor and in Unity state where the army said it pushed back rebel attacks on Friday.
'If attacked you respond'
Aguer insisted his troops would implement any truce agreed by the government and rebels but vowed they would riposte if attacked.
The death toll nationwide is said to be several thousand. The United Nations has said more than 120,000 residents have been displaced since the conflict started.
A source at the UN High Commissioner for Refugees in the Sudanese capital Khartoum told AFP that the agency was investigating reports that hundreds of South Sudanese had fled into neighbouring Sudan.
UN Secretary General Ban Ki-moon this week condemned the ethnic attacks as "a grave violation of human rights" and warned that those responsible would be "held accountable".
The United Nations sent in the first peacekeeping reinforcements on Friday -- a 72-member UN police unit from Bangladesh -- and more troops and equipments were expected to arrive Saturday.
The extra troops will almost double the size of the UNMISS mission in the country to a total of up to 12,500 soldiers and 1,300 police.
South Sudan, the world's youngest nation, became independent after a civil war that killed more than two million people between 1983 and 2005.